Mailing the story:
Viewing the Night Sky with Linux, Part III: Stellarium and Celestia Take You There
KStars and XEphem can answer pretty much any question about what's where and when in the night sky. But they don't really give you the feeling of being there like a couple of newer entries on the Linux astronomy scene: Stellarium and Celestia. Grab your red-blue 3D glasses, and follow Akkana Peck on a celestial tour.